Aurora is testing the city’s outdoor warning sirens at 11:30 a.m. Tuesday, so residents will hear a three-minute wailing sound.

The test by the  Office of Emergency Management will include more than 50 sirens throughout the city starting at 11:30 a.m. The sirens are intended to notify people outdoors to seek shelter and may not be heard indoors, according to a city news release.

Aurora tests the sirens audibly twice a year, in March and November, and silent-tests them weekly year-round.

The sirens are used in outdoor emergency situations, such as tornado warnings or hazardous material spills.

If severe weather is forecast and the sirens sound, it means a tornado warning was issued by the National Weather Service and an actual or possible tornado has been spotted within the city’s boundaries.

There is no all-clear tone that sounds when the situation has been resolved or mitigated. The sirens are a call to immediately take shelter and seek additional information from weather radio, local TV and radio stations, or the city’s social media sites.

In event of an emergency, those informational sites should be used to get information to determine when the threat has passed, the city said. Sirens will re-activate in the event of a new warning or new threat.

Residents who want to get emergency alerts directly to their phones or emails can sign up for CodeRED, the city’s emergency alert provider.

The city asked residents not to call 911 when sirens sound, as dispatch phone lines need to be kept open and available for medical emergency calls.

Aurora’s website has an example warning siren sound for residents to listen to.